Billionaire financier Warren Buffett — who previously announced that he will give away most of his fortune before or upon his death — announced this week that he is donating $2.6 billion to five charities. The donation comes in the form of stock in his company, Berkshire Hathaway.

The bulk of the donation — 17,458,431 shares worth slightly more than $2 billion — will go to the Bill & Melinda Gates Foundation, which Buffett has supported annually since 2006. Buffett donated about $1.5 billion worth of shares to the foundation at this time last year. Buffett has pledged to donate a total of 500 million Berkshire Hathaway shares to the Gates foundation, and has now donated about 168 million shares, according to CNBC.

The remaining funds went to four Buffett family foundations. About 1.75 million shares worth slightly more than $200 million will go to the Susan Thompson Buffett Foundation, which was established in honor of Buffett's late wife. The foundation offers college scholarships and runs an annual award to recognize 15 outstanding public school teachers.

The other three foundations are all run by Buffett's children and will each receive 1.22 million shares, worth about $140 million. The Sherwood Foundation, run by Buffett's daughter, Susan Alice Buffett, promotes equality and social justice initiatives in the state of Nebraska. The NoVo Foundation, run by Peter Buffett, aims to empower adolescent girls, end violence against women, and promote local economies. The Howard G. Buffett Foundation focuses on food and water security and conflict resolution in impoverished and marginalized communities.

In addition to his own donations over the years, the elder Buffett has encouraged other wealthy people to "dedicate the majority of their wealth to philanthropy" through his Giving Pledge. Other billionaires who have made the pledge include New York Mayor Michael Bloomberg, Virgin Group founder Richard Branson and business magnates Carl Icahn, Ronald Perelman and David Rockefeller. As Buffett explains on the Giving Pledge site, he hopes these donations will have an impact, but says that the sacrifices made by the families who donate their time to churches, schools and other organizations every day have an impact "far more valuable than money."